This invention relates to a sealing arrangement for a rotary slide valve which is subjected to fluctuating pressures in a pressure chamber adjacent to it, in particular to a combustion chamber of an internal combustion engine. The arrangement includes a sliding ring which, without benefit of oil lubrication, bears on the slide valve with at least one peripheral sliding surface under the effect of forces which are exerted by the pressure in the pressure chamber acting on it and by at least one spring. A housing accommodates the sliding ring. At least one sealing gasket, peripherally surrounding the sliding ring is axially held in a groove for sealing of a gap between the sliding ring and the housing.
A sealing arrangement of the above type, is known from U.S. Pat. No. 4,404,934 for the sealing of a rotary slide valve serving the control of the cylinder charge change of an internal combustion engine. It shall be understood that the rotary slide valve, within the meaning of the invention, may be a globe or flat rotary slide valve, in addition to a cylindrical rotary valve.
Contemplating the need for the application of the invention, we find that the sealing problem is worsened because the gas pressure exerted on and pressing the sliding ring against the rotary slide valve is subjected to very large fluctuations. In order for the pressure in the combustion chamber to cause a flawless contact pressure between the sliding ring and the rotary slide valve and thereby a good sealing of this site, the state of the art provides that the sliding surface be smaller than the sum of the surfaces facing the combustion chamber and the projections thereof which are subjected to the combustion chamber pressure in the direction of the rotary slide valve. At high combustion chamber pressures however, the gas pressure-generated contact pressure becomes very high and leads to high sliding surface wear.